Radio Access Network (RAN) sharing deployment scenarios are known and methods and abilities to facilitate implementations of these scenarios have been introduced into the 3G standards since Release 5.
RAN sharing provides a way for network operators (service providers) to reduce their capital expenditure requirements and/or widen the area covered by a cellular communication service when setting up a wireless communications network. Rather than each operator having to provide their own base station and associated equipment for each cell of the network, an operator sharing the RAN of another operator is able to provide their service into areas served by the other operator without having to invest in their own base stations in that location.
Furthermore, by reducing the number of base stations that must be provided and operated, the ongoing operating costs can be reduced for the sharing operators. Indeed, each base station may draw a large amount of electricity during operation, and therefore reducing the number of operating base stations may significantly reduce electrical power requirements and may therefore also be considered environmentally friendly.
Typically, sharing of RANs by operators has been a symmetric arrangement in which each operator gets some access to the RAN of the other operator. In the extreme, such an arrangement allows two operators to provide service to the same area with half as many base stations (and therefore with significantly reduced cost) as would be required if no sharing was possible.
RAN sharing is particularly advantageous in areas in which an operator has cell capacity that is underused, as this spare capacity can then be shared with no impact on the original operator's ongoing service provision. Furthermore, RAN sharing may be useful in order to ensure that a service provided by an operator is able to reach a certain percentage of the population, which may be specified by license conditions in some countries, without requiring each operator to install expensive capacity in remote areas in which it is likely to be underutilized.
Currently, the standards relating to RAN sharing are limited to two scenarios. In a first scenario, only the RAN base stations themselves are shared by the different operators. In a second scenario, parts of the core network, for example the Evolved Packet Core (EPC) in LTE, can be shared as well as the RAN base stations, further decreasing capital expenditure costs in setting up the network. In each case, sharing of the RAN can be arranged to use split frequencies, in which each operator sharing the RAN has allocated (different) frequency ranges, or may use common frequencies in which the full range of frequencies is available for use by either operator.
The mechanisms for sharing of RANs may also be useful in the case of mergers of operator companies, allowing the two operators to merge their network services without any significant interruptions in service provision.
To date, it has always been the case that the network provider that makes the RAN available for sharing has been one of the service providers, or operators, sharing the network. However, the inventors have realised that in future this may not always be the case. In particular, in some cases it is possible that a specialist network provider may install network capacity that can then be used by unrelated service providers.
The recent economic situation has provided further impetus for network operators to reduce costs, and therefore increased the trend to share networks with other operators. In particularly, network operators are increasingly considering the scenario in which the owner of the network is not themselves a service provider. In this case, each service provider, or operator, will purchase a share in the capacity of the network. This may be based on their respective holding of frequency licenses in the relevant spectrum.
The first arrangement in which a number of network operators will rely on a third party network provider to provide a shared access network has now been proposed. However, there remain a number of issues to be addressed in the standards to enable this scenario of RAN sharing to be implemented.
For example, in order to enable this new RAN sharing scenario, it is important that the standard provides ways to guarantee fair usage of the network resources by each of the network operators according to their share in the RAN. Each network operator must be able to monitor the network performance to ensure that service level agreements are met and to identify any potential problems. Furthermore, each network operator must be able to operate their share of the network in a way that provides complete access to all existing features defined in the standards.
The ability for network operators sharing capacity in a communication network to monitor the network performance in a shared RAN is also useful in enforcing sharing agreements when one of the operators is also the owner of the shared RAN and/or when the network operators are assigned different proportions of the network resources (i.e. unequal shares).